1.35pm: Minute-by-minute coverage of the prime minister's monthly meeting with the media live from 5.30pm.

5.11pm: The email from Downing Street says that Gordon Brown's "monthly press conference" will start at 5.30pm. This caused some amusement, because the last monthly press conference was in February. Brown has staged plenty of other press conferences since then, but not the hour-long, any-questions-on-anything job we'll be getting in half an hour.

And you can see why he hasn't been keen to submit himself to this kind of grilling recently. Why were the budget forecasts so quickly disowned by the IMF? If you didn't know what Damian McBride was up to, did you never wonder why he was known as "McPoison"? Why was David Cameron, and not you, the first party leader to order his MPs to repay money claimed in expenses, and the first to apologise to the public? And what does it feel like being party leader when Labour has received the lowest figures it's ever had in an opinion poll? It's not hard to think of awkward questions.

But Brown has chosen to face the press on a day when journalists will have other issues to put to him. And we're told he'll have something more to say about cleaning up the expenses system. We'll find out soon.

5.35pm: Brown has begun speaking.

5.36pm: Brown starts with a tribute to the Speaker.

5.37pm: He says it was a mark of Martin's "professionalism" that he chaired the meeting with party leaders this afternoon. Martin will make a statement to the Commons soon.

5.38pm: Brown says that he and other party leaders want to take "interim" measures before the Kelly committee reports.

5.39pm: All MPs' second homes allowance claims will be scrutinised and MPs will have to pay back money if they have received money wrongly. Two Labour MPs have already had the whip suspended.

There will also be a "tightening" of the rules. Martin will reveal more within the next two hours.

5.40pm: Brown lists the changes already agreed, such as scrapping the second home allowance for outer London MPs.

5.41pm: But the Commons has to go further. The key is to switch from self-regulation to external regulation. The Commons cannot continue to work as a "gentleman's club". Brown will set out proposals for an independent commission to take charge of MPs' pay and expenses. It would also administer MPs' fees, taking over the role of the Commons fees office. It would also maintain the register of members' interests. Parliament would have to set this up. But the government will make time available for the legislation as soon as possible.

5.42pm: A consultation document will be handed out to the journalists at the end of the press conference.

Brown wants to restore the public's trust in parliament. All opposition parties have welcomed the idea in principle.

5.43pm: Brown is now mentioning his other constitutional reforms. His constitutional reform programme has been relatively timid in the last two years, many commentators believe, but today's announcement may convince them Brown is a genuine reformer. He's keen to persuade the journalists that today's plan fits his long-stated agenda.

5.45pm: The BBC's Nick Robinson gets the first question. What does Brown says to those who think Martin has been a scapegoat? And will Martin definitely stand down as an MP?

Brown says it's up to Martin to announce whether he is quitting parliament.

5.47pm: Going back to parliament, Brown says procedures have grown up that are more reminiscent of gentlemen's clubs in the 19th century than 21st century politics. The system has not been reformed. The Commons has been "jealous" in guarding its privileges. That's why external regulation is so important.

(I'd say we need a name for this new political regulator, by the way. Ofpol?)

5.49pm: Adam Boulton from Sky asks what Brown's definition of "obeying the rules" is? Will Hazel Blears fall foul of the new Labour crackdown on those MPs who have not obeyed the rules?

Brown does not answer directly. He says that all cases will have to be investigated.

5.50pm: Tom Bradby from ITN asks Brown what he would say to members of the public who think ordinary people would get punished more severely if they behaved in a comparable way to MPs. Does Brown back Margaret Moran (the Luton MP who claimed around £20,000 for dry rot in a home many miles from her constituency)?

Brown says that Moran's behaviour was "totally unacceptable". He says that she should be investigated by the parliamentary commissioner for standards before a decision is taken. (We didn't know that case had gone to the commissioner.) It sounds likes he's just terminated Moran's career.

Jon Snow from Channel 4 News asks about Hazel Blears.

5.52pm: Brown says that Blears has paid the money back. But Moran did too. It sounds as if he's applying different standards.

Another journalist asks about an early election.

Brown says the problem is the "system", not individual MPs. That's why he is campaigning for big changes.

He is taking responsibility for making sure the system is cleaned up.

5.53pm: Andy Bell from Five News asks if there is agreement for the reform he mentioned. If there is, where does it leave the Kelly committee?

5.55pm: Brown says the paper being circulated sets out how this can be achieved. All parties "in principle" accept that this is the right thing to do.

Another journalist says anyone caught shoplifting who tried to get off by paying back the money would not get away with that. Why could Blears get away with that?

5.56pm: Brown says that Blears's behaviour was "totally unacceptable", but Blears was not breaking any rules. That's the strongest criticism he has made of Blears in public. Sounds like her government career may not last much longer.

A journalist from GMTV says voters think MPs are only changing the system because they've been "caught out".

5.57pm: Brown says he was the person who referred this to the committee on standards in public life before the Daily Telegraph even started publishing its revelations.

A reporter from Sunrise radio asks about the Tamil protests in Parliament Square.

5.58pm: Brown defends the right of the Tamils to engage in peaceful protest. He says he has spoken to the president of Sri Lanka and urged him to begin a political process to engage the Tamils.

5.59pm: Another journalist asks why Brown asked the taxpayer to pay for his Sky Sports subscription.

Brown says he will reflect on this. But he believes he has done the right thing. MPs have extra costs because they live in two places.

6.00pm: George Pascoe-Watson of the Sun asks about an early election. His paper is campaigning for an early election.

6.01pm: Brown says that the problem cannot be solved by a few personnel changes. It's the system that needs to be changed. "If I were the Sun I would be campaigning to change the system itself." Self-regulation is indefensible, Brown says.

6.03pm: Jason Beattie from the Daily Mirror asks if snobbishness paid any part in the fall of the Speaker.

Brown says Martin has given decades of public service. He is under "many, many pressures". In reflection, people will want to thank him for what he's done. The fact that he convened a meeting was a measure of his professionalism. He is part of the "reform in parliament". Some of the reforms are coming about as a result of decisions he has made.

6.04pm: Jerry Lewis from Israel Radio asks about the BNP.

6.06pm: Brown says he's come to the conclusion that radical reforms are needed. When people see Westminster politicians taking decisive action, they will give them credit. People should see the racism of the BNP.

A journalist from Metro says that the rules were so loose that Labour's decision about "breaking the rules" will not have much practical effect.

6.08pm: Brown says he has already suspended two MPs and "there may be more". The Commons has in the past jealously guarded its right to run itself. He was the first prime minister to intervene by putting down resolutions a few weeks ago to change the rules on expenses. (I'm not sure that's true; John Major intervened by setting up the committee on standards in public life, which led to the appointment of the parliamentary commissioner for standards.)

Robin Oakley from CNN asks if Brown will have "moral authority" when he talks to leaders of third world countries about good governance.

6.11pm: Brown says he will continue to press for good governance. In the past the administration of the Commons was never a matter for government, it was a matter for parliament.

When a problem is identified, you deal with it by "radical surgery, and radical surgery is what we are proposing".

A Mexican journalist asks Brown how he would convince a foreign audience that parliamentary democracy isn't in ruins.

Brown says he's showing a determination to clean up the system. When people look at the proposals, they will see that they change a system that has operated for a long time.

6.13pm: David Stringer from the Associated Press asks Brown if he's denying people the right to kick out MPs by refusing to call an early election.

Brown seems to be repeating the answer he gave to Pascoe-Watson. He wants to change the system quickly.

A Bloomberg journalist asks if the political crisis has been a relief from the financial crisis.

Brown says people want him to get on with the job of boosting the economy.

A Sunday Herald journalist asks Brown if it was a "mistake" not to make reform a priority when he became prime minister.

6.14pm: Brown says that as soon as he became prime minister he proposed parliamentary reform, relating to things like the royal prerogative. (That's true – but he didn't tackle expenses then.)

An American journalist asks if the government can deal with the big issues of the day when it is concentrating on tackling expenses.

6.15pm: Of course, says Brown. He says for much of today he was dealing with economic issues. He is determined to move the country out of recession.

6.16pm: Andy Miller from the Economist asks about wider political reform, electoral reform and Lords reform.

Brown says that's right. The constitutional reform agenda is very broad. He is very interested in how parliament can be made more accountable, other than voting or taking the government to court.

6.18pm: Over time, in a system like the British one, the executive and legislature have to be made more accountable.

An Indian journalist asks about India and terrorism.

6.19pm: Brown congratulates prime minister Manmohan Singh on his re-election. (Singh, like Brown, is a former finance minister. It must be nice for Brown to see an incumbent winning re-election.)

6.19pm: But voters are angry with individuals, Bradby says. Does he understand why people want to sit in judgment on their MPs?

6.20pm: Brown also stresses that his proposals will affect the Lords, as well as the Commons.

Instant summary:

Ofpol: Brown made a big announcement. At the start of his government career, as chancellor, he handed over the power to set interest rates to the Bank of England. Now, possibly near the end of his government career, he wants to hand over power over MPs' pay and expenses to an external regulator. He said this would end the centuries-old tradition of parliamentary self-regulation. This sounds dramatic (as Brown hoped it would), but we need to see the small print. Parliament would have to legislate for this and presumably government or parliament would appoint the head of the proposed new commission. And no parliament can bind its successor. MPs would still be able to influence their working conditions, I presume. But this scheme would almost certainly lead to a much stricter expenses regime.

Labour deselections: It sounds as if Margaret Moran is toast. Brown was challenged to explain why he thinks the Labour crackdown on MPs who broke the rules will have any effect when most MPs with extravagant claims have been able to say they were within the rules. I haven't heard a good answer to this question yet, and Brown did not really provide one. But he did suggest that some MPs whose claims were allowed could lose their seats. He said Margaret Moran's behaviour was "totally unacceptable". And he also used the same phrase about Hazel Blears, although initially he defended her, and so it wasn't entirely clear whether he intended to condemn her in the way that he did.

Are the Tories signed up? I don't know yet. But I think it was telling that he only talked about the opposition parties agreeing to the plan "in principle". Brown talked about early legislation, but he did not specify what this would mean. He also said the Lords would be affected. Will Tory peers vote this through, or will they try to block it?